Chapter 5

C. Vesicular

A student found a light-colored rock with many air holes. Which word best describes the texture of this rock? A. Felsic B. Coarse C. Vesicular D. Foliated

Igneous Rock

A(n) ___ is formed from the crystallization of magma

Magma

As each group of minerals crystallizes, it removes elements from the remaining ___ instead of adding new elements.

Elements

As each group of minerals melts, different ___ are added to the magma mixture changing its composition.

Melting Points

Because different minerals have different ___, not all parts of a rock melt at the same time.

A. Kimberlite

Diamonds are found in only one type of igneous rock. What is it called? A. Kimberlite B. Pegmatite C. Rhyolite D. Diorite

B. Under very high pressure

Diamonds can form only: A. Under very low pressure B. Under very high pressure C. Above ground D. Near radioactive elements

No. Different minerals have different melting points

Do all minerals have the same melting point?

Obsidian has a very small grain size

Does obsidian, a glassy rock, have a large grain size or a small grain size?

B. They cooled quickly

Extrusive rocks have fine-grained textures because _____ . A. They cooled inside Earth's crust B. They cooled quickly C. They cooled slowly D. They are derived from volcanoes

Lava

Gases escape form ___ as it flows out onto Earth's surface.

B. From the crystallization of magma

How are igneous rocks formed? A. From the cementation of mineral grains B. From the crystallization of magma C. From increased pressures and temperatures D. From the compaction of loose sediments

B. Lava is the surface form of magma

How are magma and lava related? A. Magma is the surface form of lava B. Lava is the surface form of magma C. Magma is lava that contains water D. Lava is magma that contains water

As pressure on the rock increases, the melting point on the rock increases

How does pressure affect the melting point of rock?

Pressure increases with depth on the weight of an overlying rock

How does pressure change with depth, and why?

Temperature increases with depth in Earth's crust

How does temperature change with depth in Earth's crust

B. Ore Deposits

Igneous intrusions often are associated with valuable: A. Radioactive Elements B. Ore Deposits C. Oil Reservoirs D. Fossil Deposits

Pegmatites

Igneous rock with extremely large-grained minerals that can contain rare ores such as lithium and beryllium.

C. Porphyritic

Igneous rock with two distinct grain sizes has a ___ texture. A. Felsic B. Fine-grained C. Porphyritic D. Coarse-grained

D. Interlocking grain textures

Igneous rocks are strong because of their: A. temperature B. Color C. Water Content D. Interlocking grain textures

C. Resistant to weathering.

Igneous rocks tend to be: A. Radioactive B. Full of gold C. Resistant to weathering. D. Vulnerable to weathering.

C. Extrusive

Igneous rocks that cool on Earth's surface are called ____ . A. Lava B. Molten C. Extrusive D. Intrusive

Extrusive

Igneous rocks that form under conditions of fast cooling are said to be ____ .

Igneous Rock

Intrusive or extrusive rock formed from the cooling of crystallization of magma or lava

Obsidian is extrusive, glassy texture without obvious grains (it probably formed as lava cooled quickly on the Earth's surface.)

Is obsidian an intrusive or extrusive igneous rock? How do you know?

Granitic

Light-colored rocks high in silica are said to be ___ .

Granitic Rocks

Light-colored, intrusive igneous rock that has high silica content

A. Silica

Magma contains many elements and comes in several different forms. Which element in magma do scientists use to classify the different forms of magma? A. Silica B. Granite C. Potassium D. Iron

Basaltic

Magma that flows out onto Earth's surface is called ___

C. Magma Crystallization

Metal-rich quartz veins are formed at the end of: A. Volcanic Eruptions B. Radioactive Decay C. Magma Crystallization D. The Cooling of Earth's crust.

Magma

Molten rock inside Earth's crust is called...

B. Higher temperatures

Oceanic crust melts at ___ than continental crust. A. Highly pressures and lower temperatures B. Higher temperatures C. Lower temperatures

A. Vein

Ore deposits such as gold sometimes are found as a(n): A. Vein B. Extrusion C. Oil Reservoirs D. Molten Rock

D. Fluids rich in silica, water, and leftover elements crystallize late in magma formation

Quartz and elements such as gold are sometimes found in veins in igneous rocks. What best explains how the veins form? A. Fluids rich in feldspar bond with the leftover elements in magma B. Fluids rich in pegmatites do not mix with the magma C. Fluids rich in water mix with the magma. D. Fluids rich in silica, water, and leftover elements crystallize late in magma formation

Kimberlite

Rare type of ultramafic rock that can contain diamonds

Basaltic

Rock such as gabbros, which is dark-colored, has low silica content, and is rich in iron and magnesium.

Granitic

Rock such as granite, which is light-colored and has high silica content

Ultramafic

Rock such as peridotite, which has low silica content and very high levels of iron and magnesium.

Porphyritic

Rock with too different-sized grains of the same mineral.

True

T or F: Heat in the upper mantle and upper mantle and. lower crust may come, in part, from the decay of radioactive elements.

True

T or F: Magma is often a slushy mix of molten rock, gases, and mineral crystals.

True

T or F: Magmas are classified as basaltic, andesitic, or rhyolitic.

True

T or F: Silica is the most abundant compound found in magma.

False

T or F: The elements found in magma are quite different from those found in Earth's crust.

False

T or F: in the laboratory rocks must be heated from 8000°C to 12,000°C before they melt.

Partial Melting

The process whereby some minerals melt at low temperatures while other minerals remain solid is called ___.

Fractional Crystallization

The process wherein different minerals form at different temperatures is called ___ .

Pegmatite

Vein of extremely large-grained minerals

D. Ultramafic rocks

What are kimberlites? A. Felsic Rocks B. Mafic Rocks C. Intermediate Rocks D. Ultramafic Rocks

A. Veins of extremely large-grained minerals

What are pegmatites? A. Veins of extremely large-grained minerals B. Magmas of differing densities C. Microscopic, interlocking crystal grains D. Small Volcanoes

A. It forms fine-grained crystals

What effect does a fast cooling rate have on grain size in igneous rocks? A. It forms fine-grained crystals B. It forms large-grained crystals C. It forms light crystals D. It forms dark crystals

C. The decay of radioactive elements

What is the source of heat inside Earth that melts rocks into magma? A. Geothermal energy B. Earth's core is hotter for no reason C. The decay of radioactive elements D. Other molten rocks

A. Geothermal gradient

What is the temperature change in Earth's crust called? A. Geothermal gradient B. Radioactive decay C. Hydrothermal gradient D. Thermal energy

B. it predicts the order in which minerals crystallize from cooling magma

What purpose does the Bowen's Reaction Series serve? A. It predicts the water content of different granites. B. It predicts the order in which minerals crystallize from cooling magma C. It predicts the depth at which different minerals are found in Earth D. It predicts at which temperatures different types of magma solidify

B. Intrusive

What term describes igneous rocks that crystallize inside Earth? A. Magma B. Intrusive C. Lava D. Extrusive

Reverse

When the magma cools, it crystallizes in the ___ order of partial melting.

A. Volume

Which does not affect the formation of magma? A. Volume B. Temperature C. Pressure D. Mineral Composition

D. Diorite

Which intrusive rock has the same composition as andesite? A. Granite B. Balsalt C. Obsidian D. Diorite

D. Volume

Which is NOT a feature used for identifying minerals? A. Hardness B. Color C. Density D. Volume

D. Olivine

Which is the first mineral to form in cooling magma? A. Quartz B. Mica C. Potassium feldspar D. Olivine

C. Rhyolitic

Which magma type contains the greatest amount of silica? A. Basaltic B. Andesitic C. Rhyolitic D. Peridotic

B. Feldspars

Which minerals are associated with the right-handed branch of Bowen's reaction series? A. Olivine and Pyroxene B. Feldspars C. Mica and Feldspars D. Quartz and biotites

A. Quartz and Feldspar

Which minerals are most common in granite? A. Quartz and Feldspar B. Plagioclase Feldspar and Amphibole C. Olivine and Pyroxene D. Quartz and Olivine

B. Glassy texture

Which observation about a rock could lead you to identify it as igneous? A. Well-defined layers B. Glassy texture C. Contains Pebbles D. Made of calcite

B. Has a glassy texture

Which observation about a rock could lead you to identify it as igneous? The rock ____ . A. Has well-defined layers B. Has a glassy texture C. Contains pebbles D. Is made of calcite

D. Mineral Slope

Which of the following is not a factor involved in the formation of magma? A. Water Content B. Temperature C. Pressure D. Mineral Slope

A. Granite

Which of the following is one of the most durable igneous rocks? A. Granite B. Sandstone C. Marble D. Limestone

B. Cooling and crystallization

Which of the following produces an intrusive igneous rock? A. Compaction and cementation of sediments below Earth's surface B. Cooling and crystallization of magma below Earth's surface C. Compaction and cementation of sediments on Earth's surface D. Cooling and crystallization of lava on Earth's surface

B. Fast Cooling

Which process formed this rock (obsidian)? A. Slow cooling B. Fast cooling C. Very fast cooling D. Slow, then fast cooling

B. Diorite

Which rock has an intermediate composition? A. Rhyolite B. Diorite C. Dunite D. Basaltic

B. Kimberlite

Which type of ultrabasic rock sometimes contains diamonds? A. Pegmatite B. Kimberlite C. Granite D. Rhyolite

D. Branches of crystallization

___ explains the relationship between cooling magma and mineral formation. A. Partial melting B. Bowen's reaction series C. Geothermal gradients D. Branches of crystallization

Rhyolitic

___ magma has the highest silica content.

Magma

______ forms deep beneath Earth's crust.

Bowen's Reaction Series

_________ of hardness describes the order in which minerals crystallize.

Vesicular Texture

characterized by containing vesicles, or holes, formed by gas bubbles

Intrusive Rocks

coarse-grained igneous rock that is formed when molten rock cools slowly and solidifies inside Earth's crust

Extrusive Rocks

fine-grained igneous rock that is formed when molten rock cools quickly and solidifies on Earth's surface

Lava

magma that flows and onto Earth's surface

Fractional Crystallization

process in which different minerals crystallize from magma at different temperatures, removing elements from magma

Kimberlites

rare, ultramafic rock that can contain diamonds and other minerals formed only under very high pressures.

Porphyritic Texture

rock texture characterized by large, well-formed crystals surrounded by finer-grained crystals of the same or different mineral

Basaltic Rocks

rock that is dark colored, has lower silica contents, and is rich in iron and magnesium; contains mostly plagioclase and pyroxene

Bowen's Reaction Series

sequential, predictable, dual-branched pattern in which minerals crystallize from cooling magma

Texture

the size, shape, and distribution of the crystals or grains that make up a rock